From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 72E11C433EF for ; Thu, 10 Feb 2022 18:58:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=GuyjcJVOEQbVZekEm13nRcoFTTD0D844UZKHlMyolwg=; b=F5bK3YJDTREv3u 8pS2JRCx5szRVO+ZuqO5l7V0/ya8I25V+4NIEh31CrujTCUQIqje8wwIwwpJnQxggpRzwUUTAHuF/ NaiBQoJqx6FVmEaZ8ueL0sP1jD8kL78eE5YbUvBjViLZS6QnBMgWzd5qZFsVrL+ilYgT/AXDAL/A+ 0EKwgXezmoNepbRScnKxcgGQZAe6YV92vaRJm7Qr7BVlOU4wuGHqi0SGWikvlbh29gMJ4ZQ/GblHK ht6N7lVkcFSC7NpoCm7VYp1I9Fm5Ps/BJIOlzk7KIZ3TQSBcJjkQTZYQWBJvHj5qepOZAd3kKfMMv y8r1v8jp01KibCY9bTpQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nIEdQ-004h2o-5n; Thu, 10 Feb 2022 18:57:40 +0000 Received: from ams.source.kernel.org ([145.40.68.75]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nIEdM-004h1O-3F for linux-arm-kernel@lists.infradead.org; Thu, 10 Feb 2022 18:57:37 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id AC3CAB8271F; Thu, 10 Feb 2022 18:57:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4D286C004E1; Thu, 10 Feb 2022 18:57:30 +0000 (UTC) Date: Thu, 10 Feb 2022 18:57:26 +0000 From: Catalin Marinas To: Mark Brown Cc: Will Deacon , Marc Zyngier , Shuah Khan , Shuah Khan , Alan Hayward , Luis Machado , Salil Akerkar , Basant Kumar Dwivedi , Szabolcs Nagy , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org, kvmarm@lists.cs.columbia.edu Subject: Re: [PATCH v11 08/40] arm64/sme: Manually encode SME instructions Message-ID: References: <20220207152109.197566-1-broonie@kernel.org> <20220207152109.197566-9-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220207152109.197566-9-broonie@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220210_105736_310201_85144336 X-CRM114-Status: GOOD ( 22.41 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Feb 07, 2022 at 03:20:37PM +0000, Mark Brown wrote: > As with SVE rather than impose ambitious toolchain requirements for SME > we manually encode the few instructions which we require in order to > perform the work the kernel needs to do. The instructions used to save > and restore context are provided as assembler macros while those for > entering and leaving streaming mode are done in asm volatile blocks > since they are expected to be used from C. > > We could do the SMSTART and SMSTOP operations with read/modify/write > cycles on SVCR but using the aliases provided for individual field > accesses should be slightly faster. These instructions are aliases for > MSR but since our minimum toolchain requirements are old enough to mean > that we can't use the sX_X_cX_cX_X form and they always use xzr rather > than taking a value like write_sysreg_s() wants we just use .inst. > > Signed-off-by: Mark Brown > --- > arch/arm64/include/asm/fpsimd.h | 25 +++++++++++++ > arch/arm64/include/asm/fpsimdmacros.h | 53 +++++++++++++++++++++++++++ > 2 files changed, 78 insertions(+) > > diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h > index cb24385e3632..c90f7f99a768 100644 > --- a/arch/arm64/include/asm/fpsimd.h > +++ b/arch/arm64/include/asm/fpsimd.h > @@ -249,6 +249,31 @@ static inline void sve_setup(void) { } > > #endif /* ! CONFIG_ARM64_SVE */ > > +#ifdef CONFIG_ARM64_SME > + > +static inline void sme_smstart_sm(void) > +{ > + asm volatile(".inst 0xd503437f"); > +} > + > +static inline void sme_smstop_sm(void) > +{ > + asm volatile(".inst 0xd503427f"); > +} > + > +static inline void sme_smstop(void) > +{ > + asm volatile(".inst 0xd503467f"); > +} I think you can use xzr with __msr_s. It would be more consistent if we had some sysregs defined to be used with __msr_s. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel